1. Field of the Invention
The present invention is directed generally to a distribution system and, more particularly, is directed to a physical distribution system for conveying, storing and retrieving articles of manufacture.
2. Description of Related Art
There are several methods or systems used for storing articles of manufacture and commodities in warehouses. A first method is based on an automatic warehouse in which the articles and commodities are automatically conveyed to shelves. A second system comprises an operator who stores the commodities by transporting the goods to open storage space. A third method, called ground placement, involves simply piling the goods on the floor of a warehouse.
The storing method based on an automatic warehouse has certain desirable features. For example, the warehouse space is efficiently and effectively used. Stock inventory information, such as the identity and quantity of stored items, may be stored in a computer system and used in connection with the addresses assigned to the shelves. Further, an inventory management data processing system in which stock inventory data is processed and updated by a computer system is possible.
There are, however, several inherent disadvantages to the automatic warehouse. A great deal of space is required to build such structures and to configure the entire warehouse for usage. Furthermore, in such warehouses, the layout designs for the shelves, the inner space of the warehouse and the conveying paths for conveying means are determined and fixed at the design stage. Accordingly, when physical distribution conditions change and the size and shapes of goods change, it is very difficult to modify the structure of the warehouse to accommodate such changes. Thus, the conventional automatic warehouse cannot flexibly cope with changes in the conditions of physical distribution. This drawback is compounded by the fact that it takes a long period of time to build such warehouses.
The two manual storage methods described above are advantageous from the standpoint that construction costs are low. Additionally, the actual locations for storing the goods may be flexibly selected. The disadvantages of manual storage methods stem from the fact that storing/unstoring management and inventory data management are poor. In such manual storage methods, ledgers and shelf cards are generally used to keep track of inventory. The inventory data, together with dates, are posted in a ledger. Each shelf is provided with a shelf card having a description of the kinds and the quantity of goods placed thereon. When storing and removing items to and from the shelf, an operator enters data relating to the identity and quantity of goods on the related card. Accordingly, every time goods are stored or removed, the related data must be recorded on the card. Since the ledger is of the book style requiring manual recording, the recording of inventory data is not reliable and is prone to human error. This is especially apparent when an inventory of stored items is made. Too much time is required to verify the ledgers with the cards.
There is, however, another storage method comprising a conveying means such as, for example, a forklift operated by an operator to convey goods. A computer system is used to send data representing an address of each shelf to the conveying means. The operator stores or removes goods on a shelf on the basis of the received data. In this method, however, an operation guide is merely indicated at the conveying means. Therefore, even when the operator mistakenly stores or removes goods from a wrong shelf location, the computer system, nevertheless, continues its operation. The result is that the inventory data stored in the computer system becomes noncoincident with actual inventory in the warehouse. This creates an additional task of having to print out the stored data of the computer system and then comparing the data with the stored items on the shelves for verification purposes, i.e., manual inventory check and verification.
In summary, there exist physical distribution systems that are not satisfactory from the standpoint of efficient and effective updating of inventory data, manufacture cost-effectiveness and efficient operability.